Expansible link strap



Nov. 14, 1961 G. ARMBRUSTER 3,008,290

EXPANSIBLE LINK STRAP Filed Aug. 6, 1959 ATTYS,

, da U'- Utlitged States Patent 3,008,290 EXPANSIBLE LINK STRAP Gunter Armbruster, Birkenfeld, Wurttemberg, Germany,

assignor to Rodi & Wienenberger Aktiengesellschaft, Pforzheim, Germany, a joint-stock company of Ger- The present invention relates to an expansible link strap for jewelry and general utility purposes, comprising box links placed crosswise of the strap and springloaded intermediate links which are withdrawable from the box links and permit expansion-or contraction of the strap.

Link straps have already become known which comprise two V-shaped intermediate links `placed in opposed symmetrical arrangement and extending through longitudinal slots in the box links from one box link into the next, said links being maintained by helical springs in contact with the ends O f said longitudinal slots. When the strap is expanded the box links move apart, the intermediate links emerge from the box links until the helical springs bear against the side walls of the box links, and in virtue of their V-shape they are at the same time squeezed together crosswise of the strap against the resistance of the helical springs. VOn relaxing the tension of the strap the box links are positively guided along, and pulled together by, the slanting edges of the extending intermediate links because these are pushed apart. It is a disadvantage of this type of strap that its expansibility is limited because the intermediate links cannot be withdrawn from the box llinks farther than the diameter of the helical springs on both sides permits. Hence when such a link strap is used as a bracelet for a wrist watch the bracelet is dificult to slip on to the wearers wrist.

It is the object of the present invention to eliminate this disadvantage.

According to the invention the intermediate links consist of two sleeves which are adapted to be telescoped together against spring resistance transversely across the strap, and which, towards the edges of the strap, have open ends into which project retaining extensions from the side walls of the box links for retaining the intermediate links by intercepting the side walls of the sleeves when fully withdrawn from the box links.

In this form of construction of the strap the intermediate links may be withdrawn from the box links to the full extent of their width, thus increasing the expansibility of the strap. Moreover, individual links may be readily removed to shorten the strap or links inserted to make it longer.

Two preferred embodiments of the subject matter of the invention are illustrated in the accompanying drawing in Which- FIG. l is a top plan view, partly in section, of a portion of a link strap, partly contracted and partly expanded;

FIG. 2 is a View similar to FIG. l, Ibut showing a portion of a contracted link strap according to another embodiment;

FIG. 3 is a similar view showing links during shortening or lengthening the strap, and

FIG. 4 is a perspective view of a pair of expanded links.

FIG. 1 shows a link strap which consists of box links A and intermediate links B. In both its longitudinal side walls 1 each box link A has longitudinal slots 2 through each of which extends the respective half of an intermediate link B to the adjacent box link A.

The intermediate links B consist of two sleeves 3 and 4. The sleeve 4 has a reduced extension 5 slidably inserted crosswise of the strap into the sleeve 3, so that the sleeves can be pushed together until their edges 31 and 41 meet. The edges 32 and 42 of the two sleeves3 and 4, which face the outer edges of the strap, are V-shaped, the Vs `facing opposite directions and bearing against the ends 21 of the longitudinal slots 2 of the box links. In opposite portions of the side walls 6 and 7 of the sleeves 3 and 4 abutments 8 are stamped out and bent inwardly in the form of lugs; between same according to the embodiment illustrated in FIG. 1 a leaf spring 9 is sprung along the side wall so as to force the sleeves 3 and 4 apart and to press their V-shaped edges 32 and 42 against the ends 21 of the longitudinal slots 2. From the ends 21 retaining extensions 10 project into the open ends 11 of the intermediate links B and limit the withdrawal of the intermediate links B from the box links A by intercepting the lateral walls 6 and 7 of the sleeves 3 and 4. When the link lstrap is expanded, the intermediate links B are pulled out through the longitudinal slots 2 of the box links against the resistance of the leaf springs 9, the sleeves-3 and 4 on account of the V-shaped configuration of their edges 32 and 42 being telescoped together until the retaining extensions 10 intercept the side walls 6 and 7 of the sleeves 3 and 4. As a result the leaf springs 9 arch and their pressure on the sleeves 3 land 4 causes the sleeves to move apart as soon as the tension on the strap relaxes, the box links lbeing positivelyv guidedk by the V-shaped edges 32 rand 42 and pulling together until they make mutualcontact again.

The same etfect may likewise be achieved by a compression spring 12, as shown in the embodiment illustrated in FIG. 2, said compression spring bearing inside the sleeves 3 and 4 with each end against an intermediate parting wall 13, said parting wall being formed by stamping out a suitable section from each lateral wall 6 and 7 of the sleeves 3 and 4, and bending the ends inwardly in suclli manner that each end forms one half of a parting wal I The sleeves 3 and 4 of the intermediate links B in both Aforms of construction are so contrived that when the strap is fully expanded the inner edges 31 and 41 will not make contact but still leave space for the sleeves 3 and 4 to be telescoped together by an amount equalling at least the length of the retaining extension 10. When the sleeves 3 and 4 are then fully telescoped together by lateral displacement of a box link A (FIG. 3) until their edges 31 and 41 meet, then said :box link A may be disengaged out of the open end 11 of the intermediate links B by first disengaging one retaining extension 10 and then the other, thus permitting additional links to be added to or removed from the strap.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description and all changes which come within the meaning and ran-ge of equivalency of the claims are therefore intended to be embraced therein.

I claim:

1. In an elongated, longitudinally expansible strap, a

pair of closed box links including abuttingly engageable side walls having confronting elongated slot portions of uniform Width therein, said `box links extending transversely of the longitudinal axis of said strap, and an intermediate link extending transversely of the longitudinal axis of said strap, said intermediate link including opposite sides slidably telescopically received in said slots of said box links, said intermediate link comprising transversely slidably telescoped sections each including outrainred Nomi-1,1961 i vrginguter canning edgessagaged ampara-. ..-eine sirname @f aaimn, ,saidimermediannkinn site ends of the slots in said'box link side Walls, and cluding opposed walls disposed within said box links, spring means normally urgingsaid intermediate link secsaid opposed walls of said intermediate link including QUS apartan@ biasingfsaidbpglinlg side wallspinto:ajbfnt-v` portions thereon abuttingly engaging said spring means. tin'geng'a'gNei-iientgsaid int 'niediate i link., ,l;a-\{i1 1g magi-5 5 7. The structure of claim. 6,-'.said box link side walls muni thicknessin.thedireetion f thewidth n including inwardly-. directed;v4 extensions :.atsaid slots rewhich is less than Asaid Width;` saidsections being-oapalzaler ceived within .opposite fends: of Said-intermediate ilinie; wie offteles'coping'to alengtll substantially equal to the length he structure oclairn `6`;=the Wall-pontionsffrfsad ofsaid slots, said spngfmeansbeingrwlgolly -withinwsaid intermediate link including pairs of `inwardly"extending inter-me ,cliatelink, whereby upon longitudinal Vseparzaticgni;10 abutment lugs,f.said spring means comprising-:a pairof ofsidfhx .linksqsa'idg slot1 ,endsfengagep portions YruilfgsaicL. transverselydisposed leaf springs. terminallyengagedvon interinedialt'efflinkaniming edges: to canse-theintermeV-ly said abutment lugs and extending transversely between diate .link 'seetionsf rto be telesoped .n .transversely relative said sections.

to theglongifndinlaxisof saidstrap and againstthgbia 9..5Ihefstrncture `of Claimr,thwallwprtionsmf said ingpress'ure of` said. spring `rneans ,A said intermediate vv1i interniediatelinkimmprisingabutinentsrzatfopposite'ends 1, sec'j'nS alidfsaidbk linke ielvdia OppQSedfabufmnt- Ofvsaid intermediate lnnextendingelngitudnalrwf said f. portions interconneeting said llinkgsa dglirniting maximum strapsaid spu'ngineans comprisinga 1campression springe longitudinalseparation ofsaid boxlinls disposed ftrlllverseiyr of; the.1'longitudinaly axisfaof said strap and terminally engaged on said abutments.

pris'ing' a Compression springwin Vsaid intermediate link i sections and normally biasing said sections apart. Y I 9p 5. The structure .of claim 1sai-dbox link side walls. 181515... Gil-gat grlltjam Oqf 17? 1 Y 214,064` Austral 1a Aug. 30, 1956 mcludmg inwardly direct-ed, xnslons afsld---SlQiSf-fe- 958 881 Germany Feb 28 1957 ceived within opposite ends of said intermediate link. 

